Treatment of coal tar acids



' trial importance.

Patented Apr. 10, 1934 UNITED STATES PArEnr oFricE versal 05! Products Company, Chicago, 111., a

corporation of South Dakota No Drawing.

Application November 15, 1929 Serial No. 407,374

2 Claims.

This invention relates to the conversion of relatively high boiling tar acids obtained from coal into products of relatively low boiling range suitable for use as wood preservatives, animal dip, mineral flotation, phenol-aldehyde condensation products and other products of much higher value than the original starting material. One of the problems in industry at the present time is the production of a smokeless fuel from bituminous coal. The deposits of bituminous coal represent the greatest known source of potential energy and lay-products so that improvements in the processing thereof and in the products obtained therefrom is of the greatest indus- Among other methods for the treatment of bituminous coal to produce a smokeless fuel and to decrease the cost of coal to the consumer is the process known as low temperature carbonization. In this process, bituminous coals are distilled at relatively low temperatures for example, approximately 500 to 600 C. compared with the ordinary carbonizetion methods which are operated at approximately 1000 to 1300 C. During this process approximately 25 gals. of tar per ton of coal carbonized is obtained and the economical success of the carbonization process depends upon the profitable disposal or utilization of low temperature coal tar. The latter in turn, depends upon the profitable utilization of the tar acids or phenols.

The present invention concerns itself with the treatment of tar acids or phenols in order to convert the relatively high boiling tar acids or phenols in coal tar to the relatively low boiling phenols for which there is a great demand. The low boiling tar acids or phenols are very useful as disinfectants and antiseptics and find particular use in the production of condensation products of phenols and aldehydes. The resins formed fromthe condensation of phenols and aldehydes are of the greatest importance in the industries. They are used in the manufacture of a great variety of articles such as artificial amber, buttons, cigar holders, pipe stems, ornamental articles, umbrella handles, grinding wheels, phonograph records, electrical appliances, varnishes, lacquers, enamels, paints, cements, and molding compounds in general. The phenols in low temperature coal tar for example, which are most useful for these purposes are present usually to the extent of less than the remaining 60% being practically useless at the present time. I have discovered that these high boiling phenols consisting of the higher homologues and the so-called acid resins or rhetinols can be converted into the lower boiling phenols V such as the cresols and phenol treatment usually under pressure my process. My process catalysts or reagents but I boiling tar acids or phenols pressure.

Usually the tar acids or phenols are separated from the coal tar preferably by distilling the latter down to a pitch or coke and extracting the tar acids or phenols from the distillate by treatment with an alkaline substance such as sodium hydroxide and thereafter liberating the tar acids or phenols from the alkaline extract by means of an acidic substance hydrochloric acid, carbamic, etc. acid. I have found that operating under pressures of from approximately 25 pounds per square inch and upwards, for example, to approximately 200 pounds that I can convert tar acids or phenols boiling for example above the boiling point of phenol and cresols into high yields of the desirable low boiling tar acids or phenols. For example, I have been able to obtain by operating at '75 lbs. pres-' sure on a 1.008 sp. gr. stock with an initial boil: ing point of approximately 450 F., approximately 75% of tar acids in the distillate containing over of the tar acids or phenols boiling below the initial boiling point of the charging stock. Similar results have also been obtained at other operating pressures. In the example the temperature was approximately 815 F. Preferably I employ a temperature of 800 to 950 F., but temperatures of approximately 750 to 1100 F. may

according to does not require the under self-generated boiling above 450 F. could be converted further into the low boiling tar acids by repeated treatments or by re-cycling in the same process. I have found that the phenols and cresols made from the higher boiling homologues have physical .i

and chemical properties which make them entirely suitable for the uses and purposes to which these products made by ordinary processes are applied for example, as antiseptics, disinfectants, resins from the condensation of the phenols and aldehydes, etc. While I prefer to crack the high boiling tar acids or phenols separately for the production of the low boiling phenols as this procedure permits me to regulate the temperature and pressure I also contemplate the use of materials containing substantial percentages of tar acids.

In the present invention I have found that the presence of water or steam while the tar acids or phenols are undergoing conversion has a propreferably heat high such as dilute sulphuric acid,

itself by heat be employed. The remaining tar acids or phenols 9 I 2 found effect upon the products and yields of the process, particularly in increasing the yields of neutral oils formed and it is among the purposes of the present invention to utilize water or steam in the conversion of these tar acids to regulate the relative yields of the various products formed. As an example of the efiect of water on the products produced from the cracking or decomposition of the high boiling tar acids, or phenols, the following data are given. It is evidentfromthe examples given that by the use of water or steam in the cracking process the maximum yields of neutral oils may be obtained when such is the desired object.

Water content of tar acid cracking stocks ,fz Per cent water 2 l0 18 26 Cracking tem. "F 875 895 880 885 Pressure, lbs 175 175 175 175 f Total water recovered during cracking Per cent water 7. 5 13.8 24. 2 29 8 Percent water produced from cracking 5. 5 3. 8 G. 2 3. 8

Tar acid decomposition as function of water present Taracids per cent pressure distil 84.5 71.6 63. 2 54.8 Tar acids per cent basis churge 41 0 30. 6 l8. 2 13.3 Tar acidsper cent basis tar acids in charge 42. 5 34. 0 22. 5 l7. 7*

Neutral oil formation from tar acid decomposition Neutral oilper cent pressure distillate 15. 5 28. 4 36. 8 45. 2 Neutral'oil per cent basis charge- 7. 7 l2. 2 10.6 10. 9 Neutral oil per cent basis tar acids in charge 7. 85 13.6 13. 1 l5. 0*

' "Yield corrected for water in charge.

I have obtained results which show, for example, that with 25% of water in the charge tar acids or phenols in the water free distillate will beapproximately compared with a tar acid or phenol content of 85% with only 2% water in the charge. Among the important effects of the addition of water to tar acids or phenols in the present process is a marked increase in gas formation at the same temperature and it is one of the objects of the present invention to utilize this phenomenon for purposes of making gas from tar acids or phenols at relatively low temperatures, for example, when the tar acids or phenols charged contained 2% of water the cubic feet of gas formed per barrel of tar acids or phenols charged was approximately 1000. When there was present 18% of water in the charge the cubic feet of gas formed per barrel of tar acids or phenols charged was approximately 1900. The gas produced from the cracking of tar acids or phenols in the present invention contained approximately 40% of hydrogen and this percentage of hydrogen did not suffer with increase in gas formation as a result of the introduction of water. While I have shown specific examples of temperatures, pressures, yields, percentages of water, etc., I have found that I obtain good results by the use of steam instead of water, both in regard to increasing the yield of neutral oils and the gas. In view of the many variations in'operating conditions which the process permits I do not wish to be limited by the specific examples and conditions shown which are for purposes of illustration only.

I claim:

1. The process of converting relatively high boiling coal tar acids separated from coal tar into lower boiling point products which comprises heating the acids under superatmospheric pressure and in the presence of water to a temperature ranging between 750 F. and 1100 F. and condensing and collecting the evolved vapors.

2. The process of converting relatively high boiling tar acids obtained by extracting the same from coal tars into lower boiling point products which comprises heating the tar acids under superatmospheric pressure and in the presence of steam to a temperature ranging between 750 F. and 1100 F. and condensing and recovering the resulting products.

JACQUE C. MORRELL. 

